Armed with a premise straight out of an ’80s trash comedy, saddling one of its lead characters with the unenviable condition of tripping an unreasonable amount of balls the entire film, and full of Lessons To Be Learned on the Holidays, Levine’s follow-up to the mediocre WARM BODIES, starring his leads from 50/50, should have been a disaster.

But thanks to a snappy script (from many key names involved with THIS IS THE END and THE INTERVIEW) and quality performances all around, it finds a groove and — most impressively — keeps getting funnier as it goes along, peaking in the third act (whereas a plague of comedies over the past couple years has been the tendency to start off strong and peter out past the halfway mark).

Gordon-Levitt seems to be doing some sort of Keanu Reeves parody but it works and he earns sympathy for his lead much in the same way he did with 50/50 — through purely earnest commitment. Mackie and Rogen provide ample support, with Rogen especially strong given that he has to be high so much of the time — and trip-out scenes are among my least favorite genre of comedy sequences. Lizzy Caplan, Mindy Kaling, and Jillian Bell are all quite good, but perhaps the best small role belongs to Michael Shannon — who had been bothering me lately with a series of hammy performances, but his quiet hilarity in this one put him back into my good graces.

Levine has shown a propensity for the made-it-real with 50/50, and here he mines some emotion from Mackie’s subplot with his mother and JGL’s grief over his dead parents, but his grasp on tone has never been better. The film never descends into maudlin or sappy, maintaining a zippy, riotous pace the whole way. A cameo late in the film had me in stitches, especially for its meta-commentary, and a key setpiece staged unironically to “Wrecking Ball” is a blissful, pop mainstream treat.